The mechanism which predispose to the development of autoimmune disorders are not fully defined. Systemic lupus erythematosus is a disease of unknown cause that affects multiple organ systems and is characterized by the presence of multiple autoantibodies that participate in immunologically mediated tissue injury. Because inflammation is a common feature at tissue sites affected by this disorder, lipid mediators of inflammation have been implicated in its pathogenesis. This protocol will examine these questions through a systematic